Circuit breakers, which are also referred to as high-voltage switches, are used in energy engineering to make or break electrical connections under load. The nominal voltages of the circuit breakers can be in the range from a few volts up to some hundred kilovolts. The switched load currents can be several tens of kiloamperes in the case of a short-circuit. For reliable operation of the circuit breaker, therefore, for example in connection with service inspections, the contact resistance of a switching contact of the electrical circuit breaker is checked. A high degree of wear can occur at the switching contact of the circuit breaker, for example burn-off of the arcing contacts, during switching under load and, in particular, during breaking of a short-circuit current.